1. Field of the Invention
The present invention relates to a system for controlling an internal combustion engine, in which the speed of the engine and other operating parameters are governed according to the presence of noise, vibration, or harshness (xe2x80x9cNVHxe2x80x9d) conditions which are sensed by appropriate sensors and processed by the vehicle""s engine controller. It should be noted in this regard that the presence of an NVH condition does not necessarily indicate that the vehicle or engine is running improperly. For example, as noted below, certain objectionable engine vibrations may occur without knocking operation.
2. Background Information
As vehicle powertrains and body structures become increasing refined, it has become necessary to treat engine-related vibrations more carefully. Particularly with premium automobiles, it is imperative that minimum objectionable vibration and noise be evidenced by the vehicle""s power plant. U.S. Pat. No. 6,167,860 illustrates a system in which failure of a electroelastic vibration isolator engine mount is masked by the use of an idle speed control; there is no attempt to determine whether any particular vibration has sufficient strength to be objectionable to a person occupying the vehicle.
The present invention is very different from the ""860 patent, by making the control of idle speed or other engine operating parameters a function of noise, vibration, harshness or other objectionable NVH conditions which may be sensed by the human operator or other occupants of a motor vehicle. In essence, a system and method according to present invention allows engine idle speed control to be a function of the driver""s projected physical response.
A system for controlling the idle speed or other operating parameter of an internal combustion engine in a motor vehicle includes an engine controller for receiving a plurality of engine operating parameters and for providing an idle speed control signal in response to the values of the parameters. At least one sensor is operatively connected with the controller for the purpose of sensing an NVH condition capable of being sensed by an occupant of the vehicle. The sensor produces an NVH signal in response to the sensing of the NVH condition. A signal processor operatively associated with controller receives the NVH signal. The signal processor also comprises a comparator for comparing characteristics of the NVH signal with a predetermined human threshold value. The controller uses the result of the comparison by the processor as one of a plurality of operating parameters for providing an idle speed control signal.
According to an aspect of the present invention, an NVH condition may comprise a vibration which may be sensed by the occupants of the vehicle, such as vibration of a vehicle structure such as a floor pan or other body panel or a seating component such as a seat track. Alternatively, the NVH condition may comprise a noise which may be sensed by occupants of the vehicle.
According to another aspect of the present invention, the signal processor, which may be housed within the engine controller itself, may comprise a filter operating in the time domain or filter operating in the frequency domain or both.
According to yet another aspect of the present invention, a method for controlling the idle speed or other operating parameter of an internal combustion engine installed in an automotive vehicle comprises the steps of sensing a NVH condition which is sensible by an occupant of the vehicle, producing an NVH signal corresponding to the sensed NVH condition, processing the NVH signal, and comparing the value of a characteristic of the processed NVH signal with a predetermined threshold value.
A method according to the present invention will alter idle speed or other controlled engine operating parameter in the event the value of a characteristic of the signal generated by an NVH sensor exceeds a threshold value. As before, an NVH condition according to present method may be a vibration which may be sensed by an occupant of the vehicle. Processing may comprise filtering of the NVH signal in the time domain or frequency domain followed by the comparison of the filtered signal with a threshold value, and correction of the idle speed or other operating parameter in the event that the threshold value is exceeded.